Apparatus for holding a wafer for use in a process chamber for fabricating a semiconductor device

ABSTRACT

An apparatus for holding a wafer for use in a process chamber for fabricating a semiconductor device, wherein there is provided a chuck for placing the wafer thereon and disposed to be movable in an up and down direction, a graphite disposed on the chuck and having at least one hole formed near an edge thereof, and a supporter for supporting the wafer to a given height having one end inserted in the hole. The graphite has sufficient conductivity to provide a temperature condition for carrying out a given process. The apparatus being capable of uniformly forming a deposition layer on a rear surface as well as a front surface of the wafer since the given process is carried out in a state wherein the wafer is supported to the given height.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus for holding a wafer for use in a process chamber in which various processes such as etching, deposition, ion implantation and the like are carried out during the fabrication of a semiconductor device.

[0003] 2. Description of Related Art

[0004] Semiconductor devices such as transistors and integrated circuits are generally fabricated by carrying out various processes comprising deposition, oxidation, photolithography, etching, ion implantation, and the like repeatedly to a wafer to form a given pattern thereon. However, as the elements incorporated into the semiconductor devices are increasingly integrated, unexpected defects are sometimes made in the semiconductor devices during the fabrication.

[0005] Selecting equipment for carrying out each of the various processes is very important in preventing unexpected defects since the semiconductor devices are fabricated by carrying out the various processes repeatedly.

[0006] Referring to FIG. 1, there is illustrated a conventional apparatus for holding a wafer for use in a single wafer type process chamber in which a process for forming a hemispherical grain (HSG), for example, is carried out.

[0007] The conventional apparatus 100 for holding a wafer 18 that is disposed in a process chamber 10 comprises a chuck 12 for supporting the wafer 18 and a loader 14 for loading the wafer 18. The chuck 12 is disposed to be movable up and down by a chuck bellows 20 that is mounted below the process chamber 10. On the chuck 12, a graphite 17 is disposed. The graphite 17 functions to transmit heat from a heater (not shown) to the wafer 18 and thereby to provide a temperature condition for carrying out the process for forming the HSG. The loader 14 for loading the wafer 18 on the graphite 17 has an axis 16 which penetrates the chuck bellows 20 to be connected to a loader bellows 22. The loader bellows 22 which is operated by an air cylinder 24 functions to move up and down the axis 16 of the loader 14. When the axis 16 is lowered by the loader bellows 22 to load the wafer 18 on the graphite 17, an upper portion of the loader 14 is inserted into an opening or groove (not shown) formed in the graphite 17 to ensure that a rear surface of the wafer 18 comes into contact with a surface of the graphite 17.

[0008] In the operation, a wafer 18 is transferred into the process chamber 10 by a device for transferring the wafer 18. After the wafer 18 is placed on the loader 14 that is in an elevated state, the upper portion of the loader 14 is slowly lowered and inserted into the groove of the graphite 17 to allow the wafer 18 to be placed on the surface of the graphite 17. A dome 26 is then closed to seal the process chamber 10. Next, a vacuum pump (not shown) is operated to make the process chamber 10 vacuous. When the process chamber 10 forms a vacuum at a given level, the process gas for forming the HSG is supplied for a given time. Consequently, a deposition layer having a given thickness is formed only on a front surface of the wafer 18.

[0009] However, when the deposition process for forming the HSG is carried out in a state wherein the wafer 18 is placed on the surface of the graphite 17, a deposition layer is formed even on an exposed surface of the graphite not covered by the wafer 18. Accordingly, as the deposition process is repeated, deposition layers or materials are accumulated to a given height on the exposed surface of the graphite. In this state, if a new wafer is placed on the graphite in order to carry out the deposition process, it can be set atop the accumulated deposition materials. Consequentially, during a subsequent deposition process, a problem occurs in that the wafer is twisted or a uniform deposition layer is not formed on the wafer.

[0010] For example, as designated at A in FIG. 2, when the wafer 18 is set atop accumulated deposition materials and a wedge-shaped space is formed below a rear surface of the wafer 18, the deposition layer is formed on the rear surface as well as the front surface of the wafer 18 during the deposition process. However, on the rear surface of the wafer 18, the deposition layer is unevenly formed due to the wedge-shaped space existing below the rear surface of the wafer 18.

[0011] The uneven deposition layer formed on the rear surface of the wafer 18 may have adverse effects on the subsequent process. For example, a thickness of the wafer having the deposition layer unevenly formed in the single wafer type process chamber is different from that of a wafer having a deposition layer evenly formed in a batch type process chamber wherein the deposition process for forming the HSG is carried out to a plurality of wafers disposed to allow their front and rear surfaces to be uniformly exposed. Therefore, when forming capacitors during the following process, a thin oxide layer is formed on the surface of the wafer formed in the single wafer type process chamber. Accordingly, process time should be extended until the required thickness is obtained and thus increasing the amount of the process gas to be supplied.

[0012] Further, since during the deposition process, a wafer arrangement in the single wafer type process chamber is fundamentally different from that in the batch type process chamber, the HSG or deposition layer is grown only on the front surface of the wafer in the single wafer type process chamber, and on both the front and rear surfaces of the wafer in the batch type process chamber. Therefore, in the following process, the process condition for the wafer obtained in the single wafer type process chamber should be determined to be different from that for the wafer obtained in the batch type process chamber.

[0013] Still further, when the loader is moved down to load the wafer on the graphite, the rear surface of the wafer comes in contact with the graphite, so that it may be scratched, which permits the formation of particles.

[0014] Also, since the loader bellows, which is apt to leak, is disposed to move the loader in an up and down direction, a problem may occur in that time is required for repairing such a leak.

SUMMARY OF THE INVENTION

[0015] Therefore, it is a feature of an embodiment of the present invention to provide an improved apparatus for holding a wafer for use in a single wafer type process chamber that can uniformly form a deposition layer on a rear surface as well as a front surface of the wafer.

[0016] It is another feature of an embodiment of the present invention to provide an improved apparatus for holding a wafer for use in a single wafer type process chamber that can process a wafer having the same deposition thickness as that of a wafer processed in a batch type process chamber.

[0017] These and other features are provided, according to an embodiment of the present invention, by an apparatus for holding a wafer for use in a process chamber for fabricating a semiconductor device comprising a chuck for placing the wafer thereon and disposed to be movable in an up and down direction, a graphite disposed on the chuck and having at least one hole formed near an edge thereof, and a supporter for supporting the wafer to a given height having one end inserted in the hole. The graphite has sufficient conductivity to provide a temperature condition for carrying out a given process.

[0018] In a preferred embodiment of the present invention, the at least one hole is three holes disposed in a shape of an equiangular triangle near the edge of the graphite.

[0019] In a preferred embodiment of the present invention, the supporter comprises a cylindrical head for supporting the wafer, wherein the cylindrical head has a rounded surface coming into contact with the wafer, a support disposed below the head to project radially from a circumferential surface of the head, and an insert disposed below the support to be inserted into the hole. Preferably, the support is ring-shaped. Also preferably, the supporter is formed of three pins inserted respectively into the three holes to support the edge of the wafer. Preferably, the supporter is formed of a material having a nature that is not changed by a process condition such as process gas, temperature, pressure and the like, such as a quartz, a silicon carbide, or a ceramic. Also preferably, the supporter is disposed beyond the range of a moving path of a device for transferring the wafer.

[0020] These and other features of the present invention will be readily apparent to those of ordinary skill in the art upon review of the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The foregoing and other features and advantages of the present invention will be apparent from the more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the present invention.

[0022]FIG. 1 illustrates a schematic cross-sectional view of a conventional apparatus for holding a wafer for use in a single wafer type process chamber according to the prior art.

[0023]FIG. 2 illustrates a partial cross-sectional view for illustrating a problem of the conventional apparatus shown in FIG. 1 according to the prior art.

[0024]FIG. 3 illustrates a schematic cross-sectional view of an apparatus for holding a wafer for use in a process chamber in accordance with a preferred embodiment of the present invention.

[0025]FIG. 4 illustrates a partial cross-sectional view of a flow of a process gas during a deposition process for forming an HSG.

[0026]FIG. 5 illustrates a perspective view of one of the pins forming a supporter of the apparatus shown in FIG. 3.

[0027]FIG. 6 illustrates a top plan view of a graphite of the apparatus shown in FIG. 3, in which three holes for receiving the supporter are formed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0028] Korean Patent Application No. 2001-35084, filed on Jun. 20, 2001, and entitled: “Apparatus for Holding a Wafer for Use in a Process Chamber for Fabricating a Semiconductor Device,” is incorporated by reference herein in its entirety.

[0029] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the present invention is shown. Like numbers refer to like elements throughout.

[0030]FIG. 3 is a schematic view of an apparatus 200 for holding a wafer for use in a process chamber in accordance with a preferred embodiment of the present invention.

[0031] The apparatus 200 of the present invention, which is disposed in a process chamber 30, comprises a chuck 32 for placing the wafer 36 thereon and supporting it. The chuck 32 is disposed to be movable in an up and down direction by a chuck bellows 34 that is mounted below the process chamber 30.

[0032] The apparatus 200 of the present invention additionally includes a graphite 40 disposed on the chuck 32. The graphite 40 has sufficient conductivity to provide a temperature condition for carrying out a given process function to transmit heat from a heater (not shown) to the wafer 36. Near an edge of the graphite 40, three holes 44, 46, 48 are formed as shown in FIG. 6. The holes 44, 46, 48 provide spaces for receiving and supporting three pins of a supporter 38 to be explained in greater detail below. Therefore, the holes 44, 46, 48 are formed so as not to interfere with the movement of a device 50 (of FIG. 6) for transferring the wafer 36. More specifically, the holes 44, 46, 48 are formed beyond the range of a movement path, indicated by an arrow in FIG. 6, of the device 50 (of FIG. 6) for transferring the wafer 36. Also, the holes 44, 46, 48 are preferably formed at equal angles or in a shape of an equiangular triangle near the edge of the graphite 40 to ensure that the pins of a supporter 38 may support the wafer 36 stably.

[0033] The apparatus 200 of the present invention further includes a supporter 38 for supporting the wafer 36 to a given height over the graphite 40 after it is transferred into the process chamber 30 by the device 50 (of FIG. 6) for transferring the wafer 36. The supporter 38 is formed of three pins for placing the wafer 36 thereon. The pins are inserted in the holes 44, 46, 48 formed near the edge of the graphite 40. Additionally, a dome 42 is provided for sealing the process chamber.

[0034] In FIG. 5, there is illustrated one of the pins forming the supporter 38. The pin 38 has a cylindrical head 380 for supporting the wafer 36. The top end of the head 380 is rounded to prevent a rear surface of the wafer 36 from being scratched and permitting the formation of particles when the wafer 36 is placed thereon. To support the wafer 36 stably, the pin includes a support 382 disposed below the head 380. Preferably, the support 382 is ring-shaped. The ring-shaped support 382 is projected radially from a circumferential surface of the head 380. Alternatively, the pin may be formed without the support 382. Also, the pin includes an insert 384 that is inserted in corresponding one of the holes 44, 46, 48 of the graphite 40. The insert 384 is formed to have a diameter and a length corresponding to those of the holes 44, 46, 48 of the graphite 40.

[0035] Preferably, the supporter 38 is formed of a material having a nature that is not changed by a process condition such as process gas, temperature, pressure and the like. For example, the supporter 38 may be formed of a quartz, a silicon carbide, a ceramic or a similar material. The supporter 38 made of the materials described above has the advantage that even though the process gas can be supplied and deposited thereon during the deposition process, substances deposited thereon can be easily removed during the maintenance and repair after finishing the process.

[0036] The operation of the apparatus 200 for holding a wafer for use in a process chamber in accordance with a preferred embodiment of the present invention will now be described.

[0037] First, the chuck 32 is moved up by the chuck bellows 34. A wafer 36 is then transferred into the process chamber 30 by the device 50 for transferring the wafer 36. After the wafer 36 is placed on the pins of the supporter 38 inserted in the holes 44, 46, 48 of the graphite 40, a dome 42 is closed to seal the process chamber 30. Then, a vacuum pump (not shown) is operated to make the process chamber 30 vacuous. When the process chamber 30 forms a vacuum at a given level, the process gas for forming the HSG is supplied for a given time. Consequently, deposition layers having a given thickness are formed on both front and rear surfaces of the wafer 36.

[0038]FIG. 4 illustrates a schematic view of the deposition process for forming the HSG. Referring to FIG. 4, when the process gas (depicted by arrows) is supplied from above or a side of the wafer 36, it begins to be deposited on a front surface of the wafer 36. At this time, the process gas is also supplied to and deposited on a rear surface of the wafer 36, since a space having a given height is formed by the pins of the supporter 38 inserted in the holes 44, 46, 48 of the graphite 40 between a surface of the graphite 40 and the rear surface of the wafer 36. Thus, the process gas is supplied to the rear surface as well as the front surface of the wafer 36 and thereby the deposition layer having a given thickness is uniformly formed on the rear surface of the wafer 36 as well as the front surface.

[0039] The thickness of the deposition layer formed on the rear surface of the wafer 36 may be varied according to the distance between the surface of the graphite 40 and the rear surface of the wafer 36, i.e., height h of the supporter 38. In the present embodiment, a preferred deposition layer can be obtained when the height h is in the range of 5 to 11 mm, and preferably 8 to 10 mm.

[0040] As is apparent from the foregoing description, it may be appreciated that in the single wafer type process chamber, the apparatus of the present invention may uniformly form a deposition layer on a rear surface as well as a front surface of the wafer since the deposition process is carried out in a state wherein the wafer is maintained to a given height.

[0041] Further, the apparatus of the present invention does not require a special device for moving the wafer in an up and down direction to load it onto the graphite, thereby reducing the cost and time required in disposing and operating the special device.

[0042] Also, the apparatus of the present invention does not need to alter the process condition for the wafer obtained in the single wafer type process chamber from that for the wafer obtained in the batch type process chamber during the following process since there is no difference in the thickness of their deposition layers.

[0043] In the drawings and specification, a preferred embodiment of the present invention has been disclosed and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims. 

What is claimed is:
 1. An apparatus for holding a wafer for use in a process chamber for fabricating a semiconductor device comprising: a chuck for placing the wafer thereon and disposed to be movable in an up and down direction; a graphite disposed on the chuck and having at least one hole formed near an edge thereof, the graphite having sufficient conductivity to provide a temperature condition for carrying out a given process; and a supporter for supporting the wafer to a given height having one end inserted in the at least one hole near the edge of the graphite.
 2. An apparatus as claimed in claim 1, wherein the supporter comprises: a cylindrical head for supporting the wafer, wherein the cylindrical head has a top end having a rounded surface coming into contact with the wafer; and an insert disposed below the support to be inserted into the hole.
 3. An apparatus as claimed in claim 2, wherein the supporter further comprises a support disposed below the cylindrical head to project radially from a circumferential surface of the head.
 4. An apparatus as claimed in claim 3, wherein the support is ring-shaped.
 5. An apparatus as claimed in claim 1, wherein the at least one hole is three holes disposed in a shape of an equiangular triangle near the edge of the graphite.
 6. An apparatus as claimed in claim 2, wherein the hole is formed of three holes disposed at an equiangular triangle shape in the edge of the graphite.
 7. An apparatus as claimed in claim 5, wherein the supporter is formed of three pins inserted respectively into the three holes to support the edge of the wafer.
 8. An apparatus as claimed in claim 6, wherein the supporter is formed of three pins inserted respectively into the three holes to support the edge of the wafer.
 9. An apparatus as claimed in claim 1, wherein the supporter is formed of a material having a nature that is not changed by a process condition such as process gas, temperature, pressure and the like.
 10. An apparatus as claimed in claim 2, wherein the supporter is formed of a material having a nature that is not changed by a process condition such as process gas, temperature, pressure and the like.
 11. An apparatus as claimed in claim 9, wherein the supporter is disposed beyond the range of a moving path of a device for transferring the wafer.
 12. An apparatus as claimed in claim 10, wherein the supporter is disposed beyond the range of a moving path of a device for transferring the wafer.
 13. An apparatus as claimed in claim 9, wherein the supporter is formed of a quartz.
 14. An apparatus as claimed in claim 10, wherein the supporter is formed of a quartz.
 15. An apparatus as claimed in claim 9, wherein the supporter is formed of a silicon carbide.
 16. An apparatus as claimed in claim 10, wherein the supporter is formed of a silicon carbide.
 17. An apparatus as claimed in claim 9, wherein the supporter is formed of a ceramic.
 18. An apparatus as claimed in claim 10, wherein the supporter is formed of a ceramic.
 19. An apparatus as claimed in claim 1, wherein the given process is a process for forming a HSG.
 20. An apparatus as claimed in claim 1, wherein the given height is in a range of 5 to 11 mm.
 21. An apparatus as claimed in claim 20, wherein the given height is in a range of 8 to 10 mm. 